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Abstract

Hydrocarbons are the principal component of insects cuticle and play an important role in maintaining water balance. Cuticular impermeability could be an adaptative response to salinity and desiccation in aquatic insects; however, cuticular hydrocarbons have been poorly explored in this group and there are no previous data on saline species. We characterized cuticular hydrocarbons of adults and larvae of two saline aquatic beetles, namely Nebrioporus baeticus (Dytiscidae) and Enochrus jesusarribasi (Hydrophilidae), using a gas chromatograph coupled to a mass spectrometer. The CHC profile of adults of both species, characterized by a high abundance of branched alkanes and low of unsaturated alkenes, seems to be more similar to that of some terrestrial beetles (e.g. desert Tenebrionidae) compared with other aquatic Coleoptera (freshwater Dytiscidae). Adults of E. jesusarribasi had longer chain compounds than N. baeticus, in agreement with their higher resistance to salinity and desiccation. The more permeable cuticle of larvae was characterized by a lower diversity in compounds, shorter carbon chain length and a higher proportion of unsaturated hydrocarbons compared with that of the adults. These results suggest that osmotic stress on aquatic insects could exert a selection pressure on CHC profile similar to aridity in terrestrial species.

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This is a submission to PeerJ for review.

Supplemental Information

Relative abundance (mean ± SE) of the cuticular hydrocarbons (CHCs) identified by GC/MS in the two studied species

S1. Relative abundance (mean ± SE) of the cuticular hydrocarbons (CHCs) identified by GC/MS in the two studied species. KI: Kovat index; n: number of larvae, males and females of the total analized where the compound is present. .

Raw data

Additional Information

Competing Interests

The authors declare that they have no competing interests.

Author Contributions

María Botella-Cruz conceived and designed the experiments, performed the experiments, analyzed the data, contributed reagents/materials/analysis tools, wrote the paper, prepared figures and/or tables, reviewed drafts of the paper.

Funding

This research was funded by the I+D+i project CGL2013-48950-C2-2-P (Spanish Ministry of Economy and Competitivity) and co-funded with Feder Funds. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

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